Set x equal to the amount of money Kim gets, and y for Molly's money.
x = 2/5y, since the ratio is 2:5.
y = 105 + x, since Molly has 105 more pounds than Kim.
Substitute x into this equation, so that y = 105 + 2/5y. Subtract 2/5y from both sides to get 3/5y = 105. Divide each side by 0.6 (equivalent to 3/5) and you get y = 175, which is how much Molly has. Kim gets 2/5 of Molly's share (or 105 fewer pounds), so she has 70.
70 + 175 (Kim and Molly's shares) is equal to 245. Therefore, Laura receives the remaining 140 pounds.
140/385 = a/100
Cross multiply so that 385a is 14000. Divide by 385 to get 36.4 (rounded).
Thus, Laura receives about 36.4% of the total money. Hope this helps (:
Let's call the younger student's age A and the older student's age B. The teacher's age will be T.
B = 2A
T = 5B
T+5 = 5(A+5)
Simplify the last equation.
T+5 = 5A+25
T = 5A+20
Now we have two equations solved for T, so we can set them equal to each other.
5B = 5A + 20
We can plug 2A in for B
5(2A) = 5A + 20
10A = 5A + 20
5A = 20
A = 4
To find T, we plug 4 in for A in T = 5A + 20
T = 5(4) + 20
T = 40
The answer is 40 years old.
